Fuel pump diaphragm leakage indicator



Dec. 8, 1970 R. F. SMITHv FUEL PUMP DIAPHRAGM LEAKAGE INDICATOR Filed Oct. 5l, 1967 FIG.v

INVENTOR RUSSELL F. SMITH I un ATTORNEY United States Patent O U.S. Cl. 340-242 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a mechanically actuated diaphragm fuel pump which includes an electrically operated alarm system adapted to provide warning or indication that the diaphragm or other part of the pump is damaged to the extent that leaking fuel has passed the diaphragm. The f'uel leak sensor comprises in effect a switch connected to a source of electricity, and an alarm mechanism. The alarm is actuated in response to the deformation or deterioration of a retaining member whic-h, when sufficiently deformed or deteriorated due to Contact with fuel or fuel vapors will permit the switch to close and actuate the alarm circuit.

BACKGROUND OF THE INVENTION The field of this invention lies primarily in fuel systems and more particularly with respect to the pumping means normally employed in fuel systems. The pump presently disclosed includes a reciprocating, flexible diaphragm used as the movable wall of the pumping chamber for urging fuel from a source, through the pump discharge. The diaphragm member is normally formed of a nonmetallic material or composition to permit the needed flexibility during motion. Such materials include reinforced fabric, rubber and the like. The diaphragm member might be considered as the weakest link in the pump structure with respect to wear or deterioration. It is understandable that over a period of time continuous flexing of the diaphragm will cause cracking and eventual rupturing of the material which will permit passing of fuel from the pumping diaphragm into the adjacent chamber.

The problem of fuel pump leakage or breakdown is particularly vexing in the instance of automobiles, boats, and other engine powered vehicles. Since the fuel pump diaphragm is relatively inaccessible, once the diaphragm has ruptured to the extent that it no longer functions to urge fuel from the source into the carburetor the supply of fuel to the engine is stopped. In many instances however the diaphragm does not rupture to the extent of rendering the pump immediately inoperative. Rather as a rule, the diaphragm initially develops a fissure which is gradually enlarged to the point where it permits a slight passage of fuel from the pumping chamber, which passage gradually enlarged due to further aggravation during diaphragm motion.

A further hazard common to fuel systems and related to the malfunction of the pump is the danger of vapor accumulations within a closed area. This is most prevalent on boats which are often constructed in a manner which minimizes the ventilation of the engine `and consequently promote the accumulation of volatile vapors within an enclosed area.

It is thus understandable, that if some pre-warning could be given of the imminent breakdown of the fuel pump, much trouble might fbe averted by timely repair, or replacement. Notably, if the initially damaged diaphragm could be replaced, or preferably the entire pump be replaced when the latter first shows signs of wear, the above noted problems would be obviated.

SUMMARY The inventive concept instantly disclosed embodies an alarm system incorporated into a fuel pump for sensing fluid in other than the pumping chamber. This alarm system comprises generally a sensor mechanism including a switch removable from the pump and connectable into an electrically powered alarm circuit having a suitable indicator device such as a bell or a warning light. The sensor member embodies at least one contact forming the switch and connected in series with the alarm circuit. Said one contact member includes spring means biasing the latter toward a second contact member such that upon electrical engagement of the two, the alarm circuit will be closed to actuate the alarm indicator. For normal operation, the second contact is maintained in spaced relation to the first contact by a deteriorative member which is characterized by being subject to physical deterioration when exposed to an atmosphere of either pumped fluid or vapors of said fluid.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation view in partial cross-section of a fuel pump of the type presently contemplated embodying a sensor switch connected to an electrically powered alarm circuit.

FIG. 2 is an enlarged segmentary view of an alternate embodiment of the sensor member shown in the pump wall.

FIG. 3 is a schematic diagram of the alarm circuit as connected with an engine ignition circuit.

DESCRIPTION OF THE INVENTION The fuel pump shown in FIG. l of the drawing is typical of a mechanically actuated diaphragm type pump which might incorporate the present fuel alarm system. The pump is similar in operation and structure to the pump shown in U.S.P. 3,333,547 D.R. Compton, et al. The function and operation of such a pump is fully described in said patent. However, the basic pumping mechanism in this type of device resides in the use of a diaphragm maintained between the pump halves, and actuated by a spring biased mechanism. The latter is in turn operahly connected to a rotating part of the engine so that the pump speed might be varied with engine speed.

As shown in the drawings, the diaphragm must be operated in such manner as to provide an expanding wall chamber. Thus, the diaphragm is subjected to a continuous flexing motion adjacent to the periphery. This continuous motion tends to prompt the formation of cracks and fissures along or near the periphery which generally form into openings which lead to fuel leakage.

Referring to FIG. 1, the pump consists basically of a open sided housing 10 which defines a cavity 11 and from which depends a casing 12. The edge of the latter is connected to the open side of housing 10 thereby defining an enclosure. Housing 10 embodies a peripheral lip 13 forming the opening to cavity 11. Casing 12 includes a rim 14 complementing lip I13 and abutting the latter to form a fluid tight circumferential seal.

Casing 12 is provided with formed wells not presently shown, but which house inlet and outlet valve so disposed to regulate liquid flow through pumping chamber 18.

A diaphragm 16 is compressibly held at its periphery intermediate the tightly clamped edges of rim 14 and lip 13. Diaphragm 16 is further maintained sufficiently tight at the edge to form a fluid tight seal thereby defining spring chamber 17 and pumping chamber 18 on opposite sides thereof. Diaphragm 16 may be partially rigidized by oppositely fastened plates 19 and 21 which extend across the respective diaphragm surfaces. Lower plate 21, as well as upper plate 19, are so formed at their periphery to impart the diaphragm a particular curved contiguration as the latter is displaced during the pumping movement.

A pump rod 22 is reciprocably, guidably received in housing in substantial alignment with the pump axis. One end of a pump arm 23 is bifurcated, forming a slotted opening adapted to receive the shank of pump rod 22 and bear against one side of cushion assembly 24. Arm 23 further includes a rubbing end extending into the engine crankcase to engage a normally rotating eccentric cam or other engine element whereby the arm is rocked through pivot pin 20. At least one wall of housing 10 defining spring chamber 17 is provided with an aperture DESCRIPTION OF THE SENSOR ELEMENT Referring to FIG. 1, the disclosed sensor assembly is shown carried within pump casing 12 and extending through a wall thereof for external connection into the electrical circuit shown in FIG. 3. The sensor assembly includes an insulated mounting grommet 27 extending through aperture 26. Said grommet is deformably held in the housing wall by a friction t or by other suitable means to maintain a predetermined position. An electrical lead element 28 extends through sealing grommet 27 and overhangs one side thereof to the interior of the pump housing 12.

A contact member 29 is carried on said electrical element 28 and is fxedly positioned thereto a predetermined distance from the interior wall of the pump housing 12. Contact member 29 includes a contact point 30 having an extending tongue depending therefrom to which is fixed a deteriorative spacer 31 which, when in position, will bias the contact member to a position away from the inner Wall of pump/housing 12.

The external portion of the electrical element 28 extends from pump housing 12 and is insulated for at least a portion of the length thereof terminating at a juncture which is adapted to electrically connect into the warning circuit.

The spacing of contact point 30 from the wall of housing 12 is dependent on the thickness of the deteriorative spacer 31. The latter is in turn formed in such a manner as to deteriorate, or collapse, preferably at a predetermined rate of speed lwhen contacted by fumes or liquid of a hydrocarbon type fuel normally carried in the fuel pump.

Referring to FIG. 2, an alternate embodiment of the sensor assembly is shown at 40 held in the wall of pump housing 41, the latter being in most respects substantially identical with the pump structure illustrated in FIG. 1. The housing wall are formed in such manner to include a raised peripheral lip 42 dening an internal cavity 43. Said cavity is provided with a central aperture 44 which communicates internally with the pump housing 41. The periphery of raised lip 42 is provided with a plurality of fastening openings such as equally spaced holes 46 adapted to receive screws 55. Said lip is further adapted to receive a resilient gasket 47 which is compressed in place by a removable panel 48 to form a iluid tight seal. Panel 48 is provided with a centrally disposed mounting 49 which accommodates an electrical connection 51 extend` ing therethrough and which is also sealably carried within said insulator member 49.

The inner side of panel 48 supports a metallic, electrically conductive cap 52 having a raised lip 53 at one end. A compression spring 54 carried on insulator 49 supports cap 52 and urges the latter away from said insulator 49. A connection 59 between cap 52 and electrical lead I51 forms a complete electrical circuit therebetween.

Cap 52 is contoured to receive and position a deteri orative member 56 which in turn, when in place, spaces the outer edge of lip 53 from the metallic wall of pump housing 41. Deteriorative member 56 may include, a rst 4 shoulder 59 supported within cap 52 and a second tip portion 57 registered in opening 44 and extending into the spring housing. Thus, protruding tip 57 of member 56 will be exposed to the fumes or liquid of the hydrocarbon type fuel being passed through the pump.

Under normal operating circumstances the pump is actuated by reciprocating diaphragm 58 to urge fuel through the pumping chamber. However, should the occasion present itself when the diaphragm ruptures or for some reason hydrocarbon fuel enters into housing 41, fuel fumes or the liquid itself will come in contact with protruding end 57 of member 56. The latter will immediately commence to deteriorate and after a predetermined period will be either shrunken or weakened to the point Where it will no longer support cup 52 away from the Walls of housing 42. Thus, coil spring 54 will bias cap `52 into Contact with the metallic housing walls thereby closing the alarm circuit and actuating the indicator mechanism.

It should be appreciated that the primary function of member 56 is to maintain two electrical components in spaced relationship under certain conditions. To this end, the precise shape and contour of member 56 may vary and still perform its desired function. Further, after the deteriorative member has performed its function by deteriorating under the effects of fuel, the alarm system may again be activated by the simple expedient of inserting a new spacer member to again separate the movable electrical component from the stationary one.

In the instance of both embodiments of the invention, the deteriorative material utilized for spacing the electrical contacting members apart is preferably a material having sufficient rigidity to maintain its spacing function between the temperatures of about -30 to 300 Fahrenheit, and yet be subject to the deleterious effects of a hydrocarbon fuel. One such material is found to be a foamed plastic such as styrofoam. The actual dimensions of the deteriorative members are variable although not arbitrary, since a feature of the invention is that the warning alarm will sound within a predetermined period of time after the pump has become affected to be most effectual.

ALARM CIRCUIT Referring to FIG. 3, one embodiment of the electrical alarm circuit herein mentioned comprises basically a source of electric current such as a low voltage battery 66 as is normally found in automotive systems, together with ignition switch 67 operable to actuate at least part of the electric system. Also included in the electrical system is a suitable signal light 68 or other indicator, preferably carried on the automobile dash where it will be visible to the vehicle operator at all times.

Following preferred practice, the electrical circuit is grounded through one side of battery 66, and includes a line 71 connecting ignition switch 67 to the electrical lead 28. The sensor element circuit is grounded to the automobile chassis or to the pump body through a condensor 69 when the alarm circuit is actuated.

With the ignition switch 67 in closed position, the circuit through signal lights 68 will not be closed until such time as the terminal 28 of the sensor element be grounded to the pump casing. Grounding of the latter is achieved only at such time as the contact point 30 is released to engage the wall of housing 10 whereby the circuit is completed through the contact 29.

Under normal operating conditions, fuel will be passed to the pump inlet, into pumping chamber 18 and then discharged through the outlet as the diaphragm 16 is reciprocated. However, should a malfunction in the diaphragm or other part of the pump occur as to permit leakage of volatile fuels into the spring compartment 17, spacer 31 will come into immediate contact either with vapors of fuel, or with the fuel itself. Over a relatively short period of time, the spacer will either partially or fully deteriorate to release the movable biased member 29 and permit the latter to be biased into engagement with the wall of the housing 10 thereby closing the alarm circuit and causing the indicator light to be actuated. This prewarning, of course, permits the vehicle operator to take the necessary precautions such as replacement of the pump to avoid a complete breakdown of the latter if the aggravated condition continues.

We claim:

1. In combination with a diaphragm pump for a volatile liquid including;

(a) ahousing,

(b) a pumping chamber having inlet and outlet means,

(c) a second chamber in said housing including a diaphragm operating device,

(d) a diaphragm separating said respective pumping and second chambers,

(e) an electrical circuit including;

(1) a source of electric current,

(2) an indicator for providing an alarm when activated to warn of the presence of vapors or volatile liquid in said second chamber,

(f) a sensing element in communication with said second chamber and integral with said electrical circuit whereby, When said sensing element is exposed to liquid or vapor of said volatile liquid, the latter will actuate said circuit thereby activating said indicator to warn of the presence of volatile liquid in said second chamber,

(g) said sensing element including contact means connected integral with said electrical circuit and being normally held in open position to maintain said indicator in non-activated condition, and a pad of deterioratable material for holding said contact means in open circuit position, said pad when exposed to vapors of said volatile liquid deteriorating thereby closing said contacts for actuating said indicator means,

(h) said housing including; an externally protruding lip defining a cavity about said aperture, said sensing element including a removable cover plate sealably positioned on said lip to form a vapor tight closure, said sensing member being mounted on said cove1 plate in said cavity and including a cup-shaped contactor, and a spacer registered in said housing aperture and in contact with said electrical member within said cup-shaped contactor.

2. In the combination as defined in claim 1, wherein said spacer is removably received in said cup-shaped contactor.

3. In the combination as dened in claim 1, including; spring means compressibly retained between said cover and said cup-shaped contactor for urging the latter toward said housing wall.

4. In the combination as dened in claim 1, wherein said cup-shaped contactor includes; a base, and a rim depending from said base in a direction toward said housing wall for contacting the latter.

5. In the combination as dened in claim 4, wherein said rim is ilared outwardly from said base to define a conical shaped cavity for receiving said spacer.

References Cited UNITED STATES PATENTS 2,043,857 6/1936 Montgomery 200-61.04X 2,049,321 7/1936 Sampson 20o-6104K 2,443,687 6/1948 Marquard 340-235X 2,432,367 12/ 1947 Andresen 200-61.04 3,304,880 2/1967 Gold et al 103-150 3,381,591 5/1968 Toschkol 103-150 FOREIGN PATENTS 185,051 5/1907 Germany 20G- 61.04 1,210,057 2/ 1966 Germany 340-235 ALVIN H. WARING, Primary Examiner D. MYER, Assistant Examiner U.S. Cl. X.R. 20G-61.04 

